SWITCH AS-LIGHT 3K1650 - Caterpillar

3500 Series Marine And Industrial EnginesReference: Service Magazine, this issue, the article "Engine Rotation Can Be Changed On 3500 Series Engines". The parts books for 3500 Series Engines give information on the 8N7500 Auxiliary Drive Chart-Gears And Installation. Three of the gears are now carburized to be used in high load applications, and have new part numbers as shown in Chart A.
In addition, some confusion exists as to the location of the front timing gears in different applications, such as adding attachments or changing the direction of rotation of an engine. Use the illustrations as a guide for correct location of the front timing gears.
The accessory drive gears and the auxiliary drive gears must always rotate in the same direction, regardless of the direction of rotation of the engine.Use Chart B for identification and application of gears shown in the illustration.
Illustration 1. Front timing gears, high speed, SAE Standard Rotation.
Illustration 2. Front timing gears, high speed, SAE Opposite Rotation.
Illustration 3. Front timing gears, slow speed, SAE Standard Rotation.
Illustration 4. Front timing gears, slow speed, SAE Opposite Rotation.